Environmental Impact of Microbial Pesticides

Biological control constitutes an important component of integrated pest management (IPM). However, the non-availability o f efficient biocontrol agents is one of the major constraints in adopting IPM practices. Microbial control, which makes use o f naturally occurring microbes to control insect pests, pathogens, and weeds, is less harmful to nontarget organisms and the environment than the chemical pesticides. Microbials are promising alternatives to chemical pesticides and have opened up new vistas in insect pest management to aid promotion o f safe, eco-friendly pest management. The use o f microbial pesticides in pest management is quite limited because o f lack of appropriate formulations and the availability of quality products to the farmers. Since 2006, the registration o f the microbial pesticides for commercial purposes has been made mandatory in India. It warrants information on toxicological results against mammals and eco-toxicity data on nontargets such as fishes, birds, earthworms, honeybees, and silkworm. The data is to be generated with technical product and the formulation of every strain intended for commercialization. It is also mandatory to generate data on the safety of the formulation to natural enemies along with data on the bioefficacy and phytotoxicity to the crop. Fourteen primary microbial pesticide products and their formulations have been registered in India by 2009. There are 478 products o f the 14 microbial pesticides registered in India. There are 184 products for the management of plant pathogen

Not Available

Not AvailableInsects are attacked by several pathogens (entomopathogens) such as bacteria, fungi, viruses, protozoa and nematodes. Entomopathogens are eco-friendly and target-specific thus holding ecological, biological and economic significance. These pathogens can sicken or kill the insects. Cessation of feeding and reproduction are generally observed in the surviving insects. Hence these pathogens have been exploited for biological control of insect pests through inundative applications. Many different types of bacteria are known to acutely or chronically infect insects. A naturally occurring insect-pathogenic bacterium Bacillus thuringiensis (Bt), is the world’s most extensively used biological control agent and is specific to certain insect orders. Bt produces several toxins like Cry, Cyt and Vip proteins that are stomach poisons and must be ingested by the plant-feeding insects for exerting toxicity. Cry toxin action is a multistage process leading to paralysis of the mid-gut resulting in feeding cessation followed by starvation and death. Initially, the activated toxins bind to receptors located on the apical microvillus membrane of epithelial midgut cells. Two important insect proteins aminopeptidase-N (APN) and Cadherins have been identified as receptors for Cry toxins. More than 240 holotype of Cry toxins have been reported under 68 major classes (Cry1 to Cry68) that are specific to various insect orders - lepidoptera (Cry1, Cry2, Cry9 and Cry15), diptera (Cry4, Cry10, Cry11, Cry16, Cry17, Cry19 and Cry20) and coleoptera (Cry3, Cry7 and Cry8). Toxins of the Cry6 class are nematicidal in nature. More than 700 species of fungi are known to infect insects out of which less than 20 have been exploited for insect pest management. These entomopathogenic fungi (EPF) have an extensive host range but need cool, humid environments to be effective. Individual strains of the same fungal species often have different host ranges or pathogenicities. Infection is by attachment of the spore to the cuticle followed by germination and secretion of chitinolytic enzymes by the germ tube. These enzymes digest the cuticle enabling invasion of the body cavity by the germ tube followed by blastospore production, mycosis and finally death. Under congenial environmental conditions, mycelial growth followed by sporulation occurs on the surface of the cadavers. Majority of these fungi secrete toxins eg. destruxins, bassianolide, beauvericin, tenellin, bassiacridin etc. that weaken their host’s immune system and could be the virulence factors involved in pathogenesis. Bt can be effectively used in combination with EPFs taking advantage of the dual mode of action for enhancing the speed of kill as well as mitigating the problem of resistance development.University of Hyderaba

Not Available

Not AvailableNot AvIn India, crops are affected by several pests including insects, diseases, weeds, rats, nematodes etc. causing 30% loss of the Indian crop yield potential amounting to more than 30 million tonnes of food grain valued at Rs.50,000 million, representing 18 % of the gross national agricultural production. Of this, 23 % loss is due to insect pests. Pest management was primarily dependant on chemical pesticides. Keeping in view the ill effects of chemical pesticides, the Govt. of India has adopted Integrated Pest Management (IPM) as the cardinal principle and main plank of plant protection strategy in the country. IPM is an eco-friendly approach aimed at minimum use of chemical pesticides by employing available alternative methods of pest control like cultural, mechanical and biological and use of bio-pesticides to maintain pest species at economically acceptable densities. Insect pathogens can have a major role in pest management but their effective integration into such systems depends on their compatibility with other components of this system such as chemical pesticides, other pathogens, parasitic and predaceous arthropods.ailableicar-iio

Not Available

Not AvailableScreening 50 isolates of Bacillus thuringiensis (Bt) kurstaki from soil samples of Rajasthan and Telangana states, India led to identification of 10 isolates promising against the polyphagous pests Spodoptera litura (Fabricius) and Helicoverpa armigera (Hübner). rep-PCR revealed distinctness of one isolate DOR Bt-127 with cry1Ac, 1Ae, 1C, 1E, 2Aa, 2Ab genes coding for toxins effective against a wide range of insect pests. Spore-crystal mixture of Bt-127 had a high spore count of 9x1022/g and delta endotoxin content 18.28%, possessed bipyramidal crystals (0.64-2.12 µm) and ellipsoidal spores (1.92-2.2 µm). SDS-PAGE resulted in a 62 kDa band corresponding to the Cry1 toxin. Potencies against the less susceptible pests S. litura and S. exigua (Hübner) were 71309 and 46205 SU/mg respectively while potencies against the susceptible pests H. armigera, Plutella xylostella (Linnaeus) and Achaea janata (Linnaeus) were 35844, 26571 and 51667 IU/mg respectively. DOR Bt-127 holds great promise for management of these important pests overcoming the need for using different Bt varieties.AMAAS 1009764

Not Available

Not AvailableThe training manual covers general techniques pertaining to microbial control of insect pests and diseases, mass production and quality control of Bacillus thuringiensis, Beauveria bassiana and Trichoderma virideICAR-IIO

Not Available

Not AvailableNot AvailableNot Availabl